1. Related Application
This application is related to Ser. No. 08/034,981, entitled, "Method of Synthesizing Poly(Vinyl Chloride) By Means of a Pseudo-Living Radical Polymerization and Product Thereof" by Philip I. Bak, et. el. filed herewith.
2. Field of Invention
The present invention relates to a simple, efficient method of synthesizing 1-chloro-1-iodoethane. More particularly, the process of the present invention comprises the addition of substantially pure and anhydrous hydrogen iodide to vinyl chloride monomer in the presence of an iodine-catalyst. Under these conditions, the reaction results in 1-chloro-1-iodoethane. 1-Chloro-1-iodoethane is especially effective as an iodine containing chain transfer agent for the apparent pseudo-living polymerization of vinyl chloride in a process mimicking a living radical polymerization as explained in our co-pending application, referenced above. The 1-chloro-1-iodoethane chain transfer agent formed according to the method of the instant application can be added to a vinyl chloride polymerization system separately after the 1-chloro-1-iodoethane is formed. Alternatively, the 1-chloro-1-iodoethane may possibly be generated in the reaction vessel prior to the polymerization of the vinyl chloride monomer. By using 1-chloro-1-iodoethane prepared by the instant invention as a chain transfer agent during polymerization of vinyl chloride monomer, a poly(vinyl chloride) polymer having low molecular weight (Mn generally less than 30,000), low polydispersity (generally less than 2.2), and good thermal stability is formed as described in our copending application referenced above.
3. Description of the Art
The addition of hydrogen iodide to vinyl chloride was first described by Kharasch and Hannum in an article in 1934. The article, entitled "The Peroxide Effect in the Addition of Reagents to Unsaturated Compounds IV. The Addition of Halogen Acids to Vinyl Chloride", J. American Chem. Soc., 56, (1934) p. 712 described the addition of various halogen acids such as hydrogen iodide to vinyl chloride. In particular, Kharasch et. al. discuss the addition of 0.12 moles of hydrogen iodide to 0.1 mole of vinyl chloride in a reactor. By these experiments, Kharasch et. al. were studying the effects of peroxides on reactions which occur via a carbocation process as opposed to a free radical process.
An attempt was made to reproduce the work of Kharasch and Hannum under modern experimental conditions. Using the Kharasch procedure, there was no 1-chloro-1-iodoethane synthesized.
However, applicants have discovered a novel process for synthesizing 1-chloro-1-iodoethane. The 1-chloro-1-iodoethane is very useful as an iodine containing chain transfer agent in the polymerization of vinyl chloride as described in our copending application referenced above. A vinyl chloride polymer having good thermal stability along with low molecular weight and low polydispersity is formed using this chain transfer agent.
Accordingly, a primary object of the present invention is to synthesize 1-chloro-1-iodoethane.
Another object of the invention is to synthesize high purity 1-chloro-1-iodoethane.
Yet an additional object of the invention is to prepare 1-chloro-1-iodoethane for use as an iodine containing chain transfer agent which can be used during polymerization of vinyl chloride monomer in a process which mimics a living radical polymerization.